For various reasons, it is often desirable to reduce the nicotine content of tobacco. For example, in recent years, low nicotine content "mild" cigarettes have gained substantial consumer acceptance.
There are numerous techniques available for reducing the nicotine content of tobacco. However, most of these techniques result in the removal of other tobacco ingredients along with the nicotine. The removal of other ingredients adversely affects desirable flavor and taste properties, or other desirable smoking qualities. Thus, there is a need for techniques which are effective to selectively reduce the nicotine content of tobacco without deleteriously modifying its desirable smoking properties.
The microbial treatment of the present invention involves the use of microorganism cultures which are specific to nicotine whereby the nicotine content of tobacco may be substantially reduced without producing any substantial effect on other components of the tobacco. While the nicotine content of tobacco is reduced, the organoleptic properties attributed to smoke generated from the tobacco are generally maintained. However, after treatment, a milder smoke is produced.
The art of tobacco fermentation has been practiced for many years in the production of cigars, chewing tobacco, and snuff. However, treatment of cigarette tobaccos by these processes is not practical because of the long times, usually days or weeks, required for completion of fermentation. These fermentation techniques also typically result in significant losses of tobacco mass, often as much as 20% to 25% of the starting dry weight.
Treatment of nicotine, including nicotine obtained from plant sources, with microorganisms effective to degrade the nicotine through a biochemical mechanism in which 6-hydroxy nicotine is formed, is known in the art. Such a technique is disclosed in U.S. Pat. No. 3,664,176. While such microorganisms are effective to degrade relatively concentrated nicotine, their use in processing tobacco during production of smoking articles, particularly cigarettes, has not been economically feasible. An extremely long contact time between the tobacco and these microorganisms is required to achieve any significant nicotine reduction under any practical operating conditions.
In accordance with the present invention, the nicotine content of tobacco can be significantly, economically and selectively reduced without adversely affecting the tobacco. The process does not increase tobacco processing time by impractical amounts, and does not involve any significant additional energy input, since the microorganisms derive their energy almost solely from nicotine contained within the tobacco. In addition, the technique of the present invention does not result in any significant loss of tobacco mass.
The present invention provides a process for the denicotinization of tobacco by inoculating the tobacco with a particular group of microorganisms, under proper conditions of temperature, moisture and pH. The microorganisms suitable for use in the present invention are those which degrade nicotine through a biochemical reaction in which 3-succinoylpyridine, as well as 6-hydroxy-3-succinoylpyridine and other by-products, are formed. The denicotinization process may be readily incorporated into conventional techniques for processing tobacco during manufacture of smoking products.